Sounds like you have a fun weekend planned!
Salamanca area= Irish Murphys, Customs House, The Telegraph (they are all within walking distance) there are a few other bars around, but these would be the more 'friendly places' and are catered for all ages, where as some of the others are for the 'youngins'
North Hobart have a few bars and pubs also, The Queens Head is a good place, they also have bands that play most Fri & Sat nights from memory (same as Customs House) people say that The Republic bar is a good place, but I have not been there for quite some time.

Meal wise, you might be better trying somewhere in North Hobart than the Waterfront, I think that most of it is overpriced for what you get. I have heard about a place that charged $35 for a fancy turkey breast meal, only to get it, and it was the processed turkey roll! Annapurna, Vanidols, Dede are nice places for something a bit more than a counter meal type meal.
I hope this helps, if you have any more questions, ask away!